What is Bela?

Bela is an embedded system for real-time audio processing with ultra-low latency. Based on the BeagleBone Black single-board computer and featuring a custom hardware and software environment, Bela integrates audio processing and sensor connectivity in a single high-performance package.

Bela was designed for audio hardware projects, but it doesn't stop there. Bela is ideal for any project that requires ultra-fast processing of multiple streams of data for maximum responsiveness. Bela is the core of many electronic musical instruments, but has also been used for kinetic sculpture, interactive installations, even a game played in an analogue oscilloscope.

Features

Built for speed

Bela uses Xenomai Linux for hard real-time audio processing with latencies as low as 100us, a speed that even the best laptop can’t match.

Code, your way

Code in C/C++, Puredata, or Faust. Use the in-browser IDE for C/C++ or your own environment. You develop it, Bela runs it.

Connect everything

Bela provides stereo audio along with 8 channels each of 16-bit analog I/O and 16 channels of digital I/O, all of which are sampled together at audio rates.

Open source

Bela’s hardware and software are both open source, and Bela benefits from the innovation and support of its worldwide community of musicians, designers, makers and tinkerers.

Embedded

Bela is powerful, but small enough to fit almost anywhere. Bela can be unplugged and run from an external battery and embed into instruments, interactive objects, effects boxes and more - no laptop required.

Browser-based IDE

Bela features a browser-based IDE, with full C/C++ development capabilities. Includes powerful features at your fingertips, such as an in-browser oscilloscope, code examples, and much more.

Projects

A selection of projects made with Bela.

Light Saber

Sound Design

Robbie’s Tiles

Instrument Design

Axis

Kinetic sculpture

Bela and an Analogue Synth

Demo

Tank Wars

Vector graphics

D-Box

Instrument Design

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Light Saber

Using the force … with Pd and Bela.

In this project Robbie and Chris explain how to make a super-sensitive audio lightsaber from a cardboard tube, an accelerometer, a piezo disc and Bela. They use Puredata for the sound design and sensor processing to make a working lightsaber fit for a Jedi! The [Heavy Compiler](//enzienaudio.com/heavy) from Enzien Audio is used to produce optimised C code from their Puredata patches to run on the board.

In the above video they walk through the steps to recreate the famous swooping sound design of the lightsaber using a looped sample of tv hum and variable delay lines. They then explain how to bring this sound model to life as a piece of interactive hardware, with an accelerometer to calculate the velocity of the cardboard tube and a piezo disc to detect impacts. This is definitely one to try at home, may the force be with you!

Robbie’s Tiles

Using Bela and piezo elements

For this project Robbie created a percussion instrument using the eight analog inputs on the Bela board. The control interface of the instrument was made with eight ceramic tiles, each with a piezo element attached to the back. Striking the tiles triggers samples, all with a latency of less than 1ms!

Axis

A kinetic sculpture

Axis is a kinetic sculpture consisting of 20 stepper motors, 20 plates made out of layered and painted paper, and one Bela.

The form and movement of Axis is based on the irrational number Phi, the number that is also the basis of the Golden Ratio. When Axis moves, its plates rotate against one another, moving constantly between order and chaos.

Bela and an Analogue Synth

A demonstration of Bela, LibPD and an analogue synth.

In this video Giulio puts Bela through its paces, showing some of the possibilities of interfacing Bela with an analogue synth. He uses libpd to run PureData patches on the board, patching the analog outputs of Bela to the CV ins of a Doepfer Dark Energy II. This demo just scratches the surface of what’s possible when Bela is used to control an analog synth (or when an analog synth is used to control Bela). It should serve as a good introduction for what can be done with the board out-of-the-box, and show how easily a Bela-based module would be to get up and running.

Giulio demonstrates some fun ways of taking control of the Dark Energy via a PureData interface. He then shows how to make things physical and connect sensors to take control of the analog synth. To take full advantage of the CV ins on the Doepfer we would need some extra circuitry but with some simple patching leads we can still achieve a lot. The frequency inputs on the Dark Energy are scaled to 1V per octave — the analog outs of Bela can produce 0-5V so we can cover a 5 octave range.

The video also includes a demonstration of how to take CV out from the analog synth and feed it into Bela. Precautions need to be taken here as the analog ins on the Bela board only tolerate 0-5V. The specs of the Dark Energy report that it gives out 0-6V but on measuring it is more like 0-8V. This would be enough to turn the Bela board into a Bela brick so we need a protection circuit. Giulio shows how to use two resistors to divide the voltage down, plus a diode from analog in to 3.3V to prevent the CV out of the synth from exceeding 4V.

Tank Wars

A game made with Bela and an analogue oscilloscope.

A simple game of launching projectiles, implemented with XY vector graphics on an oscilloscope using the Bela low-latency audio and sensor platform (http://bela.io). Bela has stereo audio in/out plus 8 channels each of 16-bit, audio-rate analog I/O, so it can generate graphics and sound simultaneously.

D-Box

A hackable musical instrument

The D-Box was the first instrument ever made with Bela and is a digital musical instrument intended to be repurposed and rewired by the performer in unusual ways. It is designed to be initially simple and constrained, but to allow the performer hack and subvert these constraints using circuit bending techniques. For more information about the rationale behind the D-box and the internal wirings of the instrument itself see: http://www.eecs.qmul.ac.uk/~andrewm/hackable.html.